The present invention relates generally to fuel tanks for vehicles and, more particularly, to a fuel permeation barrier fuel tank for a vehicle.
It is known to provide a fuel tank such as a plastic fuel tank in a vehicle to hold fuel to be used by an engine of the vehicle. When a plastic fuel tank is made, a weld line is formed by the co-extrusion of a multi-layer parison and blow molding it to form the tank, or when sheets are co-extruded, vacuum formed into two shells, and welded together to form the tank. In most cases, one of the co-extruded layers is a material that acts as a barrier to prevent excessive permeation of fuel into the atmosphere. At the weld line, continuity of this layer is not insured. As a result, a plastic fuel tank having a discontinuous permeation barrier layer made of an ethylene vinyl alcohol copolymer (EVOH) is likely to emit more fuel.
One commercial approach to resolve this concern regarding permeation is to thicken the walls of the fuel tank, which increases the weight, cost and reduces fuel capacity of the fuel tank. Another commercial approach is to protect the fuel tank by metal sheets or shields, which increases the weight and cost of the plastic fuel tank. However, there is concern that the thinner wall thickness may prevent the fuel tank from passing a flammability test.
Therefore, it is desirable to provide a fuel tank for a vehicle that has a more effective fuel permeation barrier to prevent evaporative emission. It is also desirable to provide a simplified method to seal a weld line in a plastic fuel tank for a vehicle that significantly reduces evaporative emission and cost of the fuel tank.
It is, therefore, one object of the present invention to provide a new fuel permeation barrier fuel tank for a vehicle.
It is another object of the present invention to seal a weld line in a plastic fuel tank that significantly reduces evaporative emission and cost.
To achieve the foregoing objects, the present invention is a fuel permeation barrier fuel tank for a vehicle including a tank shell having a wall formed from a plurality of layers. The layers include at least an inner layer, an outer layer, a fuel permeation barrier layer between the inner layer and the outer layer, and at least one adhesive layer being made of at least one of a chlorinated polyethylene and chlorosulfonated polyethylene disposed between either the inner layer and outer layer and the fuel permeation layer.
One advantage of the present invention is that a fuel permeation barrier fuel tank is provided for a vehicle that has a more effective fuel permeation barrier leading to less evaporative emission. Another advantage of the present invention is that the fuel permeation barrier fuel tank uses an adhesive layer between the high density polyethylene tank wall and the permeation barrier layer to effect bonding. Yet another advantage of the present invention is that the fuel permeation barrier fuel tank seals the weld line in a plastic fuel tank by deposition of a layer of the permeation barrier to cover the weld. Still another advantage of the present invention is to incorporate another layer of the adhesive layer on the outside of the barrier layer to protect against scratching or other environmental aging agents. A further advantage of the present invention is that the adhesive layer is made of chlorinated polyethylene and chlorosulfonated polyethylene, thereby lower cost of the fuel tank.
Other objects, features, and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings.